Organic light emitting diode (OLED) display device has become a very important display technique in flat plate display field due to the advantages such as thin thickness, light weight, wide viewing angle, active light emitting, continuous and adjustable emitting light color, low power consumption, wide working temperature range, simple manufacturing processes, high light emitting efficiency and the ability for flexible display.
The factors affecting the life of an OLED are various, and mainly comprise physical factors and chemical factors. For example, the physical factors comprise the combination of the function layers and the influence between the interfaces thereof, the material of the cathode, the glass transition temperature of the hole transport layer (HTL), the driving method and the like; and for example, the chemical factors comprise the oxidation of cathode, the crystallization of hole transport layer and the like. Theses factors will affect the life of organic electroluminescence device.
Moisture, oxygen or other components in the air largely affect the life of an OLED device in an OLED display device. The cathode of an OLED device generally employs a metal material such as aluminum, magnesium and calcium, whose chemical property is relatively reactive and easy to react with the permeated moisture and oxygen. Besides, the moisture and oxygen will make chemical reactions with the hole transport layer and electron transport layer of an OLED device, and these reactions will cause the invalidation of an OLED device. Therefore, it can largely enlarge the life of an OLED device by sufficiently partitioning the function layers in the OLED device and the moisture and oxygen in the atmosphere, so as to enlarge the serve life of an OLED display device.
An encapsulation method of an OLED display device generally comprises a substrate encapsulation type and a thin film encapsulation type. The substrate encapsulation type fills adhesive film between a display substrate formed with an OLED device and an encapsulation substrate, after the adhesive film being cured, the display substrate and the encapsulation substrate form a closed space therebetween, so as to achieve an encapsulation effect. The thin film encapsulation type covers a thin film encapsulation layer composed of an inorganic thin film and an organic thin film on a surface of an OLED device, so as to make the moisture and oxygen hardly permeate inside the OLED device.